I think after all the time you have put in to holding this family together in your wife's emotional and physical absence, finally reaching the point of issuing some sort of ultimatum is a very good thing.
Sometimes people change.
And sometimes they change back, other times they don't.
What reason has she had to change back?
Sometimes the ultimatum provides the motivation to change.
Lord knows that ultimatum's (of a sort) were exactly what caused most of us to finally be honest enough about ourselves that WE sought to change.
I see your situation as almost the flip side of most stories here.
While your wife has left your marriage emotionally, she refuses to leave physically.
Now YOU are the spouse finally saying, it is time for change or time to end.
It may take ending this thing before there is ever a chance she will be moved enough to WANT to change.
How far do you go?
Well, none of us should issue things like ultimatums unless we are fully prepared to see them through. You MUST go so far as to be a man of your word and do what you have said you would do.
Otherwise, your word means nothing. And you will continue to be used.
Blessings,
Bill
"Don't tell me the sky is the limit when there are footprints on the moon."